Semiconductor device

ABSTRACT

A semiconductor device includes a semiconductor substrate, an insulating film disposed above the semiconductor substrate, a temperature detecting element disposed on the insulating film, and an anode side region and a cathode side region respectively located on an anode side and a cathode side of the temperature detecting element. The anode side region or the cathode side region includes one or more capacitance elements, and a sum of capacitance values of the capacitance elements is larger than a capacitance value of the temperature detecting element.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of InternationalPatent Application No. PCT/JP2019/018394 filed on May 8, 2019, whichdesignated the U.S. and claims the benefit of priority from JapanesePatent Application No. 2018-127563 filed on Jul. 4, 2018. The entiredisclosures of all of the above applications are incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates to a semiconductor device.

BACKGROUND

There has been known a technique in which a switching element and atemperature sensing diode are formed in a semiconductor substrate, andwhen an abnormality, such as flowing of overcurrent to the switchingelement, occurs and the switching element generates heat, thetemperature sensing diode detects that to protect the switching element.

SUMMARY

The present disclosure provides a semiconductor device including asemiconductor substrate, an insulating film disposed on thesemiconductor substrate, a temperature detecting element disposed on theinsulating film, and an anode side region and a cathode side regionrespectively located on an anode side and a cathode side of thetemperature detecting element.

According to one aspect of the present disclosure, the anode side regionor the cathode side region includes one or more capacitance elements,and a sum of capacitance values of the capacitance elements is largerthan a capacitance value of the temperature detecting element.

According another aspect of the present disclosure, a resistance valueof the semiconductor substrate located under the anode side region or aresistance value of the semiconductor substrate located under thecathode side region is smaller than a resistance value of thesemiconductor substrate located under the temperature detecting element.

According to another aspect of the present disclosure, an impedanceunder the anode side region or an impedance under the cathode sideregion is smaller than an impedance under the temperature detectingelement.

BRIEF DESCRIPTION OF DRAWINGS

Objects, features and advantages of the present disclosure will becomeapparent from the following detailed description made with reference tothe accompanying drawings. In the drawings:

FIG. 1 is a vertical cross-sectional view showing a schematicconfiguration of a temperature detecting element of a semiconductordevice according to a first embodiment;

FIG. 2 is a circuit diagram showing a schematic equivalent circuit ofthe temperature detecting element of the semiconductor device accordingto the first embodiment;

FIG. 3 is a block diagram showing a schematic configuration of a Vfdetecting circuit;

FIG. 4 is a schematic configuration diagram of a DPI test apparatus;

FIG. 5 is a graph showing a capacitance value dependency of a changeamount of Vf;

FIG. 6 is a vertical cross-sectional view showing a schematicconfiguration of a temperature detecting element of a semiconductordevice according to a second embodiment;

FIG. 7 is a plan view showing a schematic configuration of a layoutexample of the temperature detecting element;

FIG. 8 is a vertical cross-sectional view showing a schematicconfiguration of a temperature detecting element of a semiconductordevice according to a third embodiment;

FIG. 9 is a vertical cross-sectional view showing a schematicconfiguration of a temperature detecting element of a semiconductordevice according to a fourth embodiment; and

FIG. 10 is a vertical cross-sectional view showing a schematicconfiguration of a temperature detecting element of a semiconductordevice according to a fifth embodiment.

DETAILED DESCRIPTION

In one configuration, a switching element is formed in a semiconductorsubstrate, and a temperature sensing diode having characteristicsdepending on temperature is provided on a front surface side of thesemiconductor substrate to be independently from the switching element.When an abnormality, such as flowing of overcurrent to the switchingelement, occurs and the switching element generates heat, thetemperature sensing diode detects that to protect the switching element.

However, in the above-described configuration, when noise enters from arear surface side of the semiconductor substrate, the noise may becoupled with a capacitance directly under the temperature sensing diode,and Vf of the diode may fluctuate, which may cause erroneous operation.

According to one aspect of the present disclosure, a semiconductordevice includes a semiconductor substrate, an insulating film disposedon the semiconductor substrate, a temperature detecting element disposedon the insulating film, and one or more capacitance elements disposed inan anode side region or a cathode side region. The anode side region islocated on an anode side of the temperature detecting element and thecathode side region is located on a cathode side of the temperaturedetecting element. A sum of capacitance values of the capacitanceelements in the anode side region or the cathode side region is largerthan a capacitance value of the temperature detecting element.

With this configuration, the capacitance value under the anode sideregion or the cathode side region can be made larger than thecapacitance value directly under the temperature detecting element. Thatis, an impedance directly under the anode side region or the cathodeside region can be made small. Accordingly, noise propagated to theanode side region or the cathode side region is predominantly absorbedby the capacitance element provided in the anode side region or thecathode side region. As a result, noise input to the temperaturedetecting element can be reduced.

Hereinafter, a plurality of embodiments of the present disclosure willbe described with reference to the drawings. In the followingdescription, the same elements as those described above are designatedby the same reference numerals, and the description thereof will beomitted. Further, in the following description and drawings, a p-typehigh concentration may be indicated by “p+”, an n-type highconcentration may be indicated by “n+”, a p-type low concentration maybe indicated by “p−”, and an n-type low concentration may be indicatedby “n−”. For example, “p+region” means a p-type high concentrationregion. Further, in the following description, lowering the impedanceincludes increasing the capacitance value and lowering the resistancevalue, and increasing the capacitance value and lowering the resistancevalue means lowering the impedance.

First Embodiment

As shown in FIGS. 1 to 3 , a semiconductor device 1 includes atemperature detecting element 20 and a switching element 40. In FIG. 1 ,a region located on an anode side of the temperature detecting element20 is referred to as an anode side region A, and a region located on acathode side of the temperature detecting element 20 is referred to as acathode side region K. The semiconductor device 1 is connected to a Vgmeasuring device 42. In the present embodiment, the temperaturedetecting element 20 is a temperature sensitive diode formed of aplurality of pn junction diodes. Vf is the forward voltage of the diodes201 to 204 forming the temperature detecting element 20.

As shown in FIG. 3 , the semiconductor device 1 includes the temperaturedetecting element 20 and the switching element 40, and is connected tothe Vf measuring device 42. The Vf measuring device 42 is connected tothe anode and cathode of the temperature detecting element 20. The Vfmeasuring device 42 measures Vf of the temperature detecting element 20.

The Vf measuring device 42 includes a Vf temperature detecting unit (VfTEMP DET) 42 a and a constant current supply unit 42 b. The Vf measuringdevice 42 measures the voltage between the anode and the cathode of thetemperature detecting element 20, that is, Vf, while applying a constantcurrent supplied from the constant current supply unit 42 b between theanode and the cathode of the temperature detecting element 20. The Vfvalue is obtained, for example, by supplying a constant current of 500μA to the temperature detecting element 20 by the constant currentsupply unit 42 b and measuring the voltage between the anode and thecathode of the temperature detecting element 20.

The temperature detecting element 20 is formed of, for example, aplurality of diodes. In the present embodiment, an example in which thetemperature detecting element 20 is formed of four diodes 201 to 204 isillustrated, but the number of diodes is not limited to four.

The switching element 40 is formed of, for example, a MOS transistor.When the switching element 40 generates heat due to driving, thetemperature of the semiconductor device 1 rises, and the temperature ofthe temperature detecting element 20 also rises. The Vf characteristicfluctuates in accordance with an increase in temperature of thetemperature detecting element 20.

The Vf measuring device 42 monitors the Vf value of the temperaturedetecting element 20 that fluctuates due to the increase in temperature.The Vf measuring device 42 is provided with, for example, aVf-temperature table (not shown) in advance, and calculates thetemperature of the switching element 40 according to the measured Vf.

Next, the switching element 40 is controlled according to the calculatedtemperature of the switching element 40. For example, when thetemperature of the temperature detecting element 20 reaches apredetermined temperature or higher, an operation clock is delayed tosuppress heat generation.

If noise enters from a rear surface of a semiconductor substrate 10, theVf of the temperature detecting element 20 fluctuates, and the Vftemperature detecting unit 42 a measures an erroneous Vf value.Accordingly, incorrect control will be implemented with respect to theswitching element 40. According to the present embodiment, since the Vffluctuation due to noise is suppressed, the above-described subject canbe solved.

FIG. 1 shows a configuration of the temperature detecting element 20including the anode side region A and the cathode side region K, andFIG. 2 shows the equivalent circuit of FIG. 1 . As shown in FIG. 1 , thetemperature detecting element 20 includes an element isolationinsulating film 12 provided on the semiconductor substrate 10, a firstinterlayer insulating film 14 provided on the element isolationinsulating film 12, and a second interlayer insulating film 16. Theelement isolation insulating film 12, the first interlayer insulatingfilm 14 provided on the element isolation insulating film 12, and thesecond interlayer insulating film 16 are insulating films provided abovethe semiconductor substrate 10. The semiconductor substrate 10 includesa low-concentration impurity region 10 a and a high-concentrationimpurity region 10 b from a side close to a semiconductor substratesurface 10 c.

For the semiconductor substrate 10, for example, an n-type singlecrystal silicon substrate can be used. The semiconductor substrate 10includes the low-concentration impurity region 10 a and thehigh-concentration impurity region 10 b. The low-concentration impurityregion 10 a and the high-concentration impurity region 10 b are formedby, for example, introduction of impurities by implantation ofhigh-energy ions and heat treatment. The low-concentration impurityregion 10 a and the high-concentration impurity region 10 b are n-typeimpurity regions, and as the impurities to be introduced, for example,phosphorus or arsenic can be used.

The element isolation insulating film 12 is formed of, for example, asilicon oxide film formed by applying a local oxidation of silicon(LOCOS) method, which is a local oxidation method, to the semiconductorsubstrate 10. The first interlayer insulating film 14 and the secondinterlayer insulating film 16 are formed by, for example, a chemicalvapor deposition (CVD) method, and are formed by, for example, a thermaldecomposition method using tetraethyl orthosilicate (TEOS) as a sourcegas, and is formed of a silicon oxide film in which phosphorus and boronare introduced during film formation. On the rear surface of thesemiconductor substrate 10, a rear surface electrode 18 is disposed, anda substrate potential is applied via the rear surface electrode 18.Noise may be input from the rear surface electrode 18.

The temperature detecting element 20 is formed on the first interlayerinsulating film 14. The temperature detecting element 20 is formed of,for example, the diodes 201, 202, 203, and 204, each of which is formedof a pair of p+diffusion layer and n+diffusion layer. The diodes 201 to204 are connected in series by connection electrodes 205, 206 and 207.

Each of the diodes 201 to 204 is formed of, for example, a p+diffusionlayer and an n+diffusion layer formed by introducing impurities intosilicon. The silicon forming the diodes 201 to 204 is formed of, forexample, polysilicon prepared by heat-treating amorphous silicon formedby a CVD method. The p+diffusion layer and n+diffusion layer areexamples of a semiconductor layer forming the temperature detectingelement 20.

The p+diffusion layers and n+diffusion layers of the diodes 201 to 204are formed by introducing impurities such as phosphorus, arsenic, andboron into polysilicon by, for example, an ion implantation method,using a photoresist formed by a lithography method as a mask. Forexample, boron is introduced into the p+diffusion layers, andphosphorus, arsenic, or the like is introduced into the n+diffusionlayers.

The p+diffusion layers and the n+diffusion layers are formed adjacent toeach other to form the pn junctions forming the diodes 201-204. In FIG.1 , the diodes 201 to 204 are arranged in this order from the anodeside, that is, the side close to the anode side region A. In each of thediodes 201 to 204, the p+diffusion layer is arranged close to the anodeside region A, and the n+diffusion layer is arranged close to thecathode side region K.

Capacitance electrodes 22 a and 26 a forming an anode capacitance 22 anda cathode capacitance 26, which will be described later, are made of thesame layer of polysilicon formed in the same process as the diodes 201to 204. In other words, the capacitance electrodes 22 a and 26 a areformed of semiconductor layers located in the same layers as thesemiconductor layer forming the temperature detecting element 20. Theanode capacitance 22 and the cathode capacitance 26 are firstcapacitance elements. Between the temperature detecting element 20formed of the diodes 201 to 204 and the rear surface electrode 18, anunder-diode capacitance 30 is formed. The capacitance value of theunder-diode capacitance 30 is defined as a capacitance value Cdi.

In FIG. 1 , the anode capacitance 22, an anode pad capacitance 24, thecathode capacitance 26, and a cathode pad capacitance 28 are formed onboth sides of the temperature detecting element 20. The anodecapacitance 22, the anode pad capacitance 24, the cathode capacitance26, and the cathode pad capacitance 28 are capacitance elements. Theanode pad capacitance 24 and the cathode pad capacitance 28 are secondcapacitance elements.

A first wiring 208 connected to the anode side of the temperaturedetecting element 20 is formed adjacent to the p+diffusion layer of thediode 201, and connects the diode 201 and the capacitance electrode 22a. A second wiring 209 connected to the cathode side of the temperaturedetecting element 20 is formed adjacent to the n+diffusion layer of thediode 204, and connects the diode 204 and the capacitance electrode 26a.

The capacitance electrode 22 a and the capacitance electrode 26 a areformed on the first interlayer insulating film 14. The capacitanceelectrodes 22 a and 26 a are made of polysilicon formed at the same timeas the diodes 201 to 204. The capacitance electrodes 22 a and 26 a areformed into n−impurity regions, for example, by introducing phosphorusat a low concentration.

The anode capacitance 22 is formed between the capacitance electrode 22a and the rear surface electrode 18. The capacitance value of the anodecapacitance 22 is defined as a capacitance value Capap. The cathodecapacitance 26 is formed between the capacitance electrode 26 a and therear surface electrode 18. The capacitance value of the cathodecapacitance 26 is defined as a capacitance value Ckcap.

An anode pad 24 a and a cathode pad 28 a are formed on the secondinterlayer insulating film 16. The anode pad 24 a and the cathode pad 28a forming the anode pad capacitance 24 and the cathode pad capacitance28, respectively, are made of metal, for example, aluminum. The anodepad 24 a and the cathode pad 28 a are electrode pads.

Between the anode pad 24 a and the cathode pad 28 a and thesemiconductor substrate 10, the element isolation insulating film 12,the first interlayer insulating film 14, and the second interlayerinsulating film 16 are narrowly interposed from a side close to thesemiconductor substrate 10. The anode pad 24 a and the cathode pad 28 aare formed in a flat plate rectangular shape, for example. The area ofeither one of the anode pad 24 a and the cathode pad 28 a is formed tobe larger than the area of the other. In the present embodiment, theanode pad 24 a has a larger area than the cathode pad 28 a.

The anode pad capacitance 24 is formed between the anode pad 24 a andthe rear surface electrode 18. The capacitance value of the anode padcapacitance 24 is defined as a capacitance value Ca. The cathode padcapacitance 28 is formed between the cathode pad 28 a and the rearsurface electrode 18. The capacitance value of the cathode padcapacitance 28 is defined as a capacitance value Ck.

Since the anode pad 24 a has the larger area than the cathode pad 28 a,the relationship between the capacitance values is that the capacitancevalue Ca> the capacitance value Ck. Further, the capacitance value ofthe anode side region A, that is, the sum of the anode capacitance 22and the anode pad capacitance 24 is set to be larger than theunder-diode capacitance 30 of the temperature detecting element 20. Inthis case, the following expression (1) is established.Capacitance value Ca+capacitance value Capap>capacitance value Cdi  (1)

As described above, the sum of the capacitance values of the anodecapacitance 22 and the anode pad capacitance 24, that is, thecapacitance value of the anode side region A, “capacitance valueCa+capacitance value Capap” is larger than the capacitance value Cdi ofthe temperature detecting element 20. When noise enters the rear surfaceelectrode 18, since the capacitance value of the anode side region A islarger than the capacitance value of the temperature detecting element20, the noise is predominantly absorbed by the capacitance of the anodeside region A, that is, the anode capacitance 22 and the anode padcapacitance 24. As a result, the influence of noise on the temperaturedetecting element 20 can be reduced, so that it is possible to providethe semiconductor device 1 capable of reducing erroneous operation ofthe temperature detection element 20 due to noise.

Further, in the present embodiment, when the sum of the anode sidecapacitance and the cathode side capacitance is larger than thecapacitance of the temperature detecting element 20, noise ispredominantly absorbed by the anode side capacitance and the cathodeside capacitance, that is, the anode capacitance 22, the anode padcapacitance 24, and the cathode capacitance 26, and the cathode padcapacitance 28. As a result, the influence of noise on the temperaturedetecting element 20 can be reduced, so that it is possible to providethe semiconductor device 1 capable of reducing erroneous operation ofthe temperature detection element 20 due to noise.

FIG. 4 is a block diagram showing a schematic configuration of a directpower injection method (DPI) test apparatus 46. The DPI test is a testin which noise is directly injected into each terminal of an IC bycapacitive coupling and the change amount of Vf of the temperaturedetecting element 20 is measured. If the change amount of Vf is large,there is a high possibility to cause erroneous operation of thetemperature detecting element 20.

As shown in FIG. 4 , the anode of the temperature detecting element 20is connected to an RF/DC terminal of a bias tee 501. The cathode of thetemperature detecting element 20 is connected to an RF/DC terminal of abias tee 502. The bias tees 501 and 502 are connected to a constantcurrent source 48, whereby a constant current is supplied to thetemperature detecting element 20.

A drain terminal of the switching element 40 is connected to a bias tee503, which is a noise source. A constant current source and a voltmeterare connected between the bias tees 501 and 502. The change amount of Vfof the temperature detecting element 20 can be measured using the DPItest apparatus 46.

FIG. 5 is a plot of the change amount of Vf with respect to thecapacitance ratio of the capacitance value Cdi of the temperaturedetecting element 20 and the sum of the capacitance value Ca of theanode capacitance 22 and the capacitance value Capap of the anode padcapacitance 24. According to FIG. 5 , the change amount of Vf decreaseswith increase in the capacitance ratio.

Further, there is an inflection point at the capacitance ratio of 20.5,and in a region of the capacitance ratio higher than 20.5, theimprovement in the change amount of Vf is not so much seen with respectto the increase in the capacitance ratio. That is, even if thecapacitance ratio is set to be 20.5 or more, the effect of reducing thechange amount of Vf is reduced. Therefore, the capacitance ratioprovided in the anode side region A or the cathode side region K has alarge effect of improving the change amount of Vf with respect to theincrease in the capacitance ratio up to about 20.5, but when thecapacitance ratio is further increased, the improvement in the changeamount of Vf with respect to the increase in the capacitance ratiobecomes small.

According to the semiconductor device 1 of the first embodiment, thefollowing effects are obtained. In the anode side region A, the sum ofthe capacitance values of the anode capacitance 22 formed of thecapacitance electrode 22 a and the anode pad capacitance 24 formed ofthe anode pad 24 a (capacitance value Ca+capacitance value Capap) is setto be larger than the capacitance value of the under-diode capacitance30 (capacitance value Cdi) formed between the temperature detectingelement 20 and the semiconductor substrate 10. That is, the impedancedirectly under the anode side region A is smaller than the impedancedirectly under the temperature detecting element 20. Accordingly, noiseinput to the temperature detecting element 20 can be reduced.

In the present embodiment, since the area of the capacitance electrode22 a is set to be larger than the area of the capacitance electrode 26a, the capacitance value is large. That is, the impedance directly underthe anode side region A is smaller than the impedance directly under thetemperature detecting element 20. Further, the area of the anode pad 24a is set to be larger than the area of the cathode pad 28 a.Accordingly, noise input to the temperature detecting element 20 can bereduced.

Further, at this time, even if the capacitance ratio of the capacitancevalue Cdi of the temperature detecting element 20 and the sum of thecapacitance value Ca of the anode capacitance 22 and the capacitancevalue Capap of the anode pad capacitance 24 is set to 20.5 or more, theeffect of reducing the change amount of Vf is not improvedsignificantly. That is, a sufficiently effective capacitance ratio canbe obtained when the capacitance ratio is 20.5 or more, and it is notnecessary to further increase the capacitance ratio.

In the first embodiment, an example in which the capacitance value ofthe anode side region A is set to be large has been described, but thecapacitance value of the cathode side region K may be set to be large.In this case, in the cathode side region K, the sum of the capacitancevalues of the cathode capacitance 26 formed of the capacitance electrode26 a and the cathode pad capacitance 28 formed of the cathode pad 28 a(capacitance value Ck+capacitance value Ckcap) is set to be larger thanthe capacitance value of the under-diode capacitance 30 (capacitancevalue Cdi) formed between the temperature detecting element 20 and thesemiconductor substrate 10. That is, the impedance directly under thecathode side region K is smaller than the impedance directly under thetemperature detecting element 20. Here, capacitance value Ca<capacitancevalue Ck is established. Further, the following expression (2) isestablished.Capacitance value Ck+capacitance value Ckcap>capacitance value Cdi  (2)

Even in this case, the same effect is obtained.

Second Embodiment

Next, a semiconductor device 1 according to a second embodiment will bedescribed. As shown in FIGS. 6 and 7 , in the second embodiment, ananode capacitance 55 in the anode side region A is formed in an activeregion 60. More specifically, a capacitance electrode 55 a forming theanode capacitance 55 is formed on an oxide film 60 a in the activeregion 60.

The oxide film 60 a in the active region 60 is formed as, for example, agate oxide film of a MOS transistor formed in the active region 60, andhas a very thin film thickness. Therefore, since the anode capacitance55 is formed between the capacitance electrode 55 a and thesemiconductor substrate 10 via the oxide film 60 a, which is thin, thecapacitance value can be increased. That is, the impedance directlyunder the anode side region A is smaller than the impedance directlyunder the temperature detecting element 20.

According to the semiconductor device 1 of the second embodiment,effects similar to the effects of the first embodiment can be obtained.Further, according to the semiconductor device 1 of the secondembodiment, since the capacitance value of the anode capacitance 55 canbe further increased, the effects can be further improved than the firstembodiment.

Third Embodiment

Next, a semiconductor device 1 according to a third embodiment will bedescribed. As shown in FIG. 8 , in the third embodiment, in an anode padcapacitance 62 in the anode side region A, a high-dielectric substance64 is provided as an insulator formed between an anode pad 62 a and theelement isolation insulating film 12. Therefore, since thehigh-dielectric substance 64 having a high dielectric constant isnarrowly interposed between the anode pad 62 a and the semiconductorsubstrate 10, the capacitance value of the anode pad capacitance 62 canbe increased.

According to the semiconductor device 1 of the third embodiment, effectssimilar to the effects of the first embodiment can be obtained. Further,according to the semiconductor device 1 of the third embodiment, thecapacitance value of the anode pad capacitance 62 can be furtherincreased. That is, the impedance directly under the anode side region Ais smaller than the impedance directly under the temperature detectingelement 20. Therefore, the effects can be further improved than thefirst embodiment.

Fourth Embodiment

Next, a semiconductor device 1 according to a fourth embodiment will bedescribed. As shown in FIG. 9 , in the fourth embodiment, a filmthickness of an oxide film 68 formed between the anode pad 66 a and theelement isolation insulating film 12 is reduced in the anode padcapacitance 66 in the anode side region A. Specifically, the anode pad66 a is disposed above the element isolation insulating film 12. Sincethe distance between the anode pad 66 a and the semiconductor substrate10 becomes small, the capacitance value of the anode pad capacitance 66can be increased. That is, the impedance directly under the anode sideregion A is smaller than the impedance directly under the temperaturedetecting element 20.

According to the semiconductor device 1 of the fourth embodiment,effects similar to the effects of the first embodiment can be obtained.Further, according to the semiconductor device of the fourth embodiment,since the capacitance value of the anode pad capacitance 66 can be setto be further increased, the effects can be further improved than thefirst embodiment.

Fifth Embodiment

Next, a semiconductor device 1 according to a fifth embodiment will bedescribed. In the fifth embodiment, as shown in FIG. 10 , in thesemiconductor substrate 10 under the capacitance electrode 22 a and theanode pad 24 a, which are in the anode side region A, and under thecapacitance electrode 26 a and the cathode pad 28 a, which are in thecathode side region K, high-concentration (HIGH CONC) impurity regions70 and 72 are formed instead of the low concentration impurity region 10a formed in the first embodiment.

In the present embodiment, the high-concentration impurity regions 70and 72 are provided as high-concentration n-type regions. Therefore, inthe semiconductor substrate 10 under the capacitance electrode 22 a andthe anode pad 24 a, which are in the anode side region A, and under thecapacitance electrode 26 a and the cathode pad 28 a, which are in thecathode side region K, the high-concentration impurity region 10 b andthe high-concentration impurity regions 70 and 72 are provided from therear surface side.

Further, in the semiconductor device 1 according to the fifthembodiment, a low-concentration impurity region 74 is provided under thetemperature detecting element 20. In the present embodiment, thelow-concentration impurity region 74 is provided as a low-concentrationn-type region.

In the above configuration, the high concentration impurity regions 70,72 and the concentration impurity region 10 b are provided in thesemiconductor substrate 10 under the capacitance electrode 22 a and theanode pad 24 a, which are in the anode side region A, and under thecapacitance electrode 26 a and the cathode pad 28 a, which are in thecathode side region K, while the low concentration impurity region 74and the high concentration impurity region 10 b are provided in thesemiconductor substrate 10 under the temperature detecting element 20.

Therefore, the electric resistance of the semiconductor substrate 10under the capacitance electrode 22 a and the anode pad 24 a, which arein the anode side region A, and under the capacitance electrode 26 a andthe cathode pad 28 a, which are in the cathode side region K, is set tobe low compared with the electric resistance of the semiconductorsubstrate 10 under the temperature detecting element 20. That is, theimpedances directly under the anode side region A and the cathode sideregion K are smaller than the impedance directly under the temperaturedetecting element 20.

According to this configuration, noise that has entered from the rearsurface of the semiconductor substrate 10 propagates to the side withthe smaller resistance, that is, the side with the smaller impedance, sothat noise is more likely to propagate to the anode side region A or thecathode side region K than the temperature detecting element 20.Therefore, when noise enters from the rear surface of the semiconductorsubstrate 10, the propagation of the noise to the temperature detectingelement 20 can be suppressed. Therefore, effects similar to the firstembodiment can be further improved.

Although the present disclosure has been made in accordance with theembodiments, it is understood that the present disclosure is not limitedto such embodiments and structures. The present disclosure encompassesvarious modifications and variations within the scope of equivalents.Furthermore, various combinations and aspects, and other combination andaspect including only one element, more than one element or less thanone element, are also within the sprit and scope of the presentdisclosure.

The above-described embodiments have described examples in which a meansof increasing the capacitance and reducing the resistance is used as ameans of lowering the impedance, but the means of lowering the impedanceis not limited to such a means in a range not deviating from the scopeof the present disclosure.

What is claimed is:
 1. A semiconductor device comprising: asemiconductor substrate; an insulating film disposed above thesemiconductor substrate; a temperature detecting element, comprising aplurality of diodes, disposed on the insulating film; a capacitanceelectrode disposed on the insulating film and physically separated fromthe temperature detecting element; and an electrode pad connected withthe capacitance electrode and physically separated from the temperaturedetecting element, wherein the capacitance electrode and the electrodepad are disposed in at least one of an anode side region and a cathodeside region, the anode side region located on an anode side of thetemperature detecting element and the cathode side region located on acathode side of the temperature detecting element, a first capacitanceelement is formed between the capacitance electrode and thesemiconductor substrate, and a second capacitance element is formedbetween the electrode pad and the semiconductor substrate, and a sum ofcapacitance values of the first capacitance element and the secondcapacitance element is larger than a capacitance value of a capacitanceelement formed between the temperature detecting element and thesemiconductor substrate.
 2. The semiconductor device according to claim1, wherein the capacitance electrode and the electrode pad are disposedin both of the anode side region and the cathode side region, and theelectrode pad in one of the anode side region and the cathode sideregion has an area larger than an area of the electrode pad in the otherof the anode side region and the cathode side region.
 3. Thesemiconductor device according to claim 1, wherein the capacitanceelectrode and the electrode pad are disposed at least in the anode sideregion.
 4. A semiconductor device comprising: a semiconductor substrate;an insulating film disposed above the semiconductor substrate; atemperature detecting element, comprising a plurality of diodes,disposed on the insulating film; a capacitance electrode disposed on theinsulating film and physically separated from the temperature detectingelement; and an electrode pad connected with the capacitance electrodeand physically separated from the temperature detecting element, whereinthe capacitance electrode and the electrode pad are disposed in at leastone of an anode side region and a cathode side region, the anode sideregion located on an anode side of the temperature detecting element andthe cathode side region located on a cathode side of the temperaturedetecting element, and a combined capacitor impedance of (i) a capacitorimpedance formed between the capacitance electrode and the semiconductorsubstrate and Ea a capacitor impedance formed between the electrode padand the semiconductor substrate is smaller than a capacitor impedanceformed between the temperature detecting element and the semiconductorsubstrate.